<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<script type="text/javascript">
			/* a+=5等价于a=a+5其他算术运算符也一样 */
			var a=25;
			a+=5;
			console.log("a="+a);
		</script>
	</head>
	<body>
	</body>
</html>